C nha bn

had

I had build sandcastles on the beach.

120^o

\(\widehat{DBC}\)= 120^o

collecting

I am going participate in a stamp collecting club .

a)\(A=x^2y^3+xy\)

\(khix=1vày=\dfrac{1}{2}tacó:\)

\(A=1^2\left(\dfrac{1}{2}\right)^3+1\times\dfrac{1}{2}\)

\(A=\dfrac{1}{8}+\dfrac{1}{2}\)

\(A=\dfrac{5}{8}\)

b)\(B=4x^3+x-2022\)

\(khi\left|x\right|=2tacó:\)

\(B=4\times2^3+2-2022\)

\(B=4\times8+2-2022\)

\(B=32+2-2022\)

\(B=-1988\)

Các phần tử của B là:

\(k=2\Rightarrow\left(2\cdot2+1\right)\left(2+3\right)=25\)

\(k=3\Rightarrow\left(2\cdot3+1\right)\left(3+3\right)=42\)

\(k=4\Rightarrow\left(2\cdot4+1\right)\left(4+3\right)=63\)

\(\Rightarrow B=\left\{25;42;63\right\}\)

Cíu e với ạ, e cảm ơn

\(a,ĐK:a>0;a\ne4\\ b,M=\dfrac{a+2\sqrt{a}+a-2\sqrt{a}}{\left(\sqrt{a}-2\right)\left(\sqrt{a}+2\right)}\cdot\dfrac{\left(\sqrt{a}-2\right)\left(\sqrt{a}+2\right)}{2\sqrt{a}}\\ M=\dfrac{2a}{2\sqrt{a}}=\sqrt{a}\\ b,M>3\Leftrightarrow\sqrt{a}>3\Leftrightarrow a>9\)

a: ĐKXĐ: \(a>0;a\ne4\)

-2x + 10 = -4

-2x = (-4) - 10

-2x = -14

x = (-14) : (-2)

x = 7

-2x=-14

    x=7